Fluted filter media

ABSTRACT

Fluted filter media includes filter material having a plurality of flutes formed therein having alternating ends of adjacent flutes closed to force fluid through filter material. A first embodiment of the filter media includes tapered flutes which have the open ends of the flutes larger in cross-section than the closed flutes, wherein the upstream open flutes converge toward the downstream end and the upstream closed end flutes diverge toward the downstream end. A second embodiment includes filter media which is asymmetric formed with dissimilar upstream and downstream flute cross-sections with larger flute openings to the upstream side of the filter. A third embodiment includes filter media with an upstream edge crushed to improve flow at the upstream edge. A fourth embodiment includes filter media with the upstream sealing material recessed from the upstream edge for reducing effects from blockages at the upstream edge of the filter.

CROSS REFERENCE RELATED APPLICATION

The present application is a continuation of application Ser. No.12/069,660, filed Feb. 11, 2008. application Ser. No. 12/069,660 is adivisional of application Ser. No. 10/371,825, filed Feb. 21, 2003, thatissued as U.S. Pat. No. 7,329,326. application Ser. No. 10/371,825 is adivisional of application Ser. No. 09/580,091, now abandoned, filed May30, 2000, which is a divisional of application Ser. No. 08/639,220, nowabandoned, filed Apr. 26, 1996. The disclosures of application Ser. Nos.12/069,660, 10/371,825, 09/580,091, and 08/639,220 are incorporatedherein by reference

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to fluted filter media, and in particular,to fluted filter media having flutes which minimize restriction acrossthe filter.

2. Prior Art

Pleated filters which utilize filter media to remove contaminants fromfluids are commonly known and take on many configurations.

A common problem with filters is inadequate filter surface area. Priorattempts to improve filtering surface area for a given filter volumehave not been entirely successful. Pleated filters are commonly usedwhich utilize a pleated filter media in an attempt to overcome thisshortcoming. Although pleated filter material may increase the filterarea, as the pleats are placed closer and closer together, therebyplacing more and more filter media in a given volume, the pleats arepressed tighter and tighter together, thereby restricting the flow. Thisrestriction may cause the velocity of flow to increase in order to passthrough the filtering media, thereby increasing the pressuredifferential across the filter which may cause additional problems inthe system.

Most permeable filter media does not provide structural support so thatthe filters require housings for supporting the filtering material. Thisincreases manufacturing costs as well as the mass and size of thefilter.

To improve restriction and provide increased media area, as well asfilter efficiency, fluted filter configurations may be utilized. Flutedfilters have the capability of increased media area per unit volume, aswell as less restriction and substantially straight-through flow.

Although fluted filters provide improved flow characteristics andefficiency over prior filter designs, fluted filters have thepossibility of greater efficiency and improved flow characteristics. Thesealed upstream ends of flutes provide a substantial blockage of theflow, and when combined with the filter material, more than half of theavailable cross sectional area of the fluid flow is blocked. Filterdesigns which have greater cross sectional area transverse to the flowprovide improved flow and restriction characteristics.

It can be seen that new and improved filters are needed which provideself support, improved restriction, improved flow characteristics, andgreater efficiency. In particular, fluted filters should have a leadingedge which provides less resistance and takes up less of thecross-sectional flow area than standard flute designs. In addition, thecross-sectional area of the filter media and the closed ends of theflutes at the upstream edge should be smaller than the opening area atthe upstream edge of the flutes. Such improved filter designs shouldalso be easily manufactured without undue additional steps. The presentinvention addresses these as well as other problems associated withfilter designs.

SUMMARY OF THE INVENTION

The present invention is directed to a fluted filter device, and inparticular, to fluted filter media with improved flow characteristics.

According to a first embodiment of the present invention, fluted filtermedia includes a fluting center sheet intermediate a top and bottomlayer. It can be appreciated that the filter media may be wound orotherwise stacked so that only a single sheet need be attached to afluting sheet, as adjacent layers will serve as either the top or bottomsheet of the next adjacent layer. In addition, the layers may be woundin a spiral configuration. Alternating ends of adjacent chambers formedby the fluted material are blocked on either the upstream or downstreamside. The first embodiment has tapered flutes which widen from one endto the other. The fluted chambers having their upstream end closed widento an open downstream end. Conversely, the downstream closed flutedchambers widen to an open upstream end.

It can be appreciated that with this configuration, the area of thefilter media transverse to the upstream flow includes a large portionopen to the chambers for receiving the flow. As the flow filters throughthe various filter material sheets, the filtered fluid passes through anenlarged downstream end as well. In this manner, the restriction due tothe filter is substantially decreased over standard fluted filtermaterials. In addition, the percentage of bead material and the upstreamedge of the filter sheets is substantially less than the open areareceiving the upstream flow.

According to a second embodiment of the present invention, fluted filtermedia includes asymmetric flutes which have a substantially sharp peakand a widened trough. The area above the trough is open to the upstreamflow. In this manner, the upstream openings at the edge of the filtermedia have a larger cross sectional area transverse to the flow than thearea of the closed flutes and the upstream edge of the filter material.This configuration provides improved flow with greater filter efficiencyand reduced restriction across the filter.

According to a third embodiment of the present invention, fluted filtermedia includes a crushed upstream edge providing for improved flow.According to the third embodiment, the leading edge of the filter mediaincludes beads blocking alternating chambers of the filter flutes. Theupstream edge of the bead and fluting sheet are angled so that a widenededge intercepts the flow and angles toward the downstream end. As theflow intercepts the upstream edge, only the leading sheeting edgecontacts the upstream flow and the bead and fluting sheet anglerearward. With this configuration, the resistance and proportion of thefilter media intercepting the upstream flow at the leading edge of thefilter is reduced. Therefore, improved flow is attained which providesfor increased efficiency and reduced restriction across the filter.

These and various other advantages and features of novelty whichcharacterize the invention are pointed out with particularity in theclaims annexed hereto and forming a part hereof. However, for a betterunderstanding of the invention, its advantages, and the objects obtainedby its use, reference should be made to the drawings which form afurther part hereof, and to the accompanying descriptive matter, inwhich there is illustrated and described a preferred embodiment of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, wherein like reference letters and numerals designatecorresponding elements throughout the several views:

FIG. 1 shows a perspective view of a first embodiment of double-facedfluted filter media having tapered flutes according to the principles ofthe present invention;

FIGS. 2A-2B show diagrammatic views of the process of manufacturing thefilter media shown in FIG. 1;

FIG. 3 shows an end elevational view of the filter media shown in FIG.1;

FIG. 4 shows an end elevational view of a roller for forming the filtermedia shown in FIG. 1;

FIG. 5 shows a detailed end view of the teeth for the roller shown inFIG. 4;

FIG. 6 shows a perspective view of a second embodiment of filter mediahaving asymmetric flutes according to the principles of the presentinvention;

FIG. 7 shows an end elevational view of the filter media shown in FIG.6;

FIG. 8 shows an end elevational view of a roller for forming the filtermedia shown in FIG. 6;

FIG. 9 shows a perspective view of a third embodiment of filter mediahaving crushed leading flute edges according to the principles of thepresent invention;

FIG. 10 shows an end elevational view of the filter media shown in FIG.9;

FIG. 11 shows a side sectional view of the leading edge of the filtermedia shown in FIG. 9;

FIG. 12 shows a graph of pressure drop across the filter versus airflowthrough the filter for various fluted filter media designs;

FIG. 13 shows a graph of pressure drop versus dust loading for variousfluted filter media designs;

FIG. 14 shows a sectional view of a fourth embodiment of filter mediahaving upstream sealed flutes with a sealed portion recessed from theupstream edge of the filter media according to the principles of thepresent invention;

FIG. 15 shows a side elevational view of a method of forming the leadingedge of the filter media shown in FIGS. 9-11; and,

FIG. 16 shows a side elevational view of a sheet of filter media cutinto strips utilizing the method shown in FIG. 15.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, and in particular to FIG. 1, there isshown a portion of a layer of double-faced permeable fluted filtermedia, generally designated 100. The first embodiment of the flutedfilter media 100 includes a multiplicity of tapered flute chambers 102.The flute chambers 102 are formed by a center fluting sheet 108 formingalternating peaks 104 and troughs 106 between facing sheets 110,including a first facing sheet 112 and a second facing sheet 114. Thetroughs 106 and peaks 104 divide the flutes 102 into an upper row andlower row. In the configuration shown in FIG. 1, the upper flutes formflute chambers 122 closed at the downstream end, while upstream closedend flute chambers 120 are the lower row of flute chambers. The flutedchambers 120 are closed by first end bead 124 completely filling asection of the upstream end of the flute between the center flutingsheet 108 and the second facing sheet 114. Similarly, a second end bead126 closes the downstream end of alternating flutes 102. Adhesive tacksconnect the peaks 104 and troughs 106 of the flutes 102 to the facingsheets 112 and 114. The flutes 102 and end beads 124 and 126 provide afilter element which is structurally self-supporting without a housing.

During filtration, unfiltered fluid enters the flute chambers 122 whichhave their upstream ends open, as indicated by the shaded arrows. Uponentering the flute chambers 122, the unfiltered fluid flow is closed offby the second end bead 126 at the downstream end. Therefore, the fluidis forced to proceed through the fluting sheet 108 or face sheets 110.As the unfiltered fluid passes through the fluting sheet 108 or facesheets 110, the fluid is filtered through the filter media layers, asindicated by the unshaded arrow. The fluid is then free to pass throughthe flute chambers 120, which have their upstream end closed and to flowout the open downstream end out the filter media 100. With theconfiguration shown, the unfiltered fluid can filter through the flutedsheet 108, the upper facing sheet 112 or lower facing sheet 114, andinto a flute chamber 120 blocked on its upstream side.

Referring now to FIGS. 2A-2B, the manufacturing process for flutedfilter media, which may be stacked or rolled to form filter elements, asexplained hereinafter, is shown. It can be appreciated that when thefilter media is layered or spiraled, with adjacent layers contacting oneanother, only one facing sheet 110 is required as it can serve as thetop for one fluted layer and the bottom sheet for another fluted layer.Therefore, it can be appreciated that the fluted sheet 108 need beapplied to only one facing sheet 110 when the layers are stacked orrolled.

As shown in FIG. 2A, a first filtering media sheet 30 is delivered froma series of rollers to opposed crimping rollers 44 forming a nip. Therollers 44 have intermeshing wavy surfaces to crimp the first sheet 30as it is pinched between the rollers 44. As shown in FIG. 2B, the firstnow corrugated sheet 30, and a second flat sheet of filter media 32 arefed together to a second nip formed between one of the crimping rollers44 and an opposed roller 45. A sealant applicator 47 applies a sealant46 along the upper surface of the second sheet 32 prior to engagementbetween the crimping roller 44 and the opposed roller 45. At thebeginning of a manufacturing run, as the first sheet 30 and second sheet32 pass through the rollers 44 and 45, the sheets fall away. However assealant 46 is applied, the sealant 46 forms first end bead 38 betweenthe fluted sheet 30 and the facing sheet 32. The peaks 26 and troughs 28have tacking beads 42 applied at spaced intervals along their apex orare otherwise attached to the facing sheet 32 to form flute chambers 34.The resultant structure of the facing sheet 32 sealed at one edge to thefluted sheet 30 is single-faced layerable filter media. If the layersare stacked or spiraled, a second bead is applied at an opposite edge tothe fluted sheet 30. If the layers are not stacked or spiraled, a secondbead is applied at an opposite edge and a second facing sheet isapplied.

Referring again to FIG. 1, it can be appreciated that the flutes 102taper. The fluted chambers 120 having their upstream end closed, widenalong the trough to an enlarged downstream opening, as shown in FIG. 3.Similarly, chambers 122 have a large upstream opening, also shown inFIG. 3, and taper to a narrowed closed end. In this manner, the portionof the filter media intercepting the upstream flow that is open issubstantially increased. In addition, as the fluid flows along theflutes and passes through the walls of the filter media, either centersheet 108 or facing sheets 112 or 114, the fluid will flow out anenlarged open end on the downstream side of the filter.

It can be appreciated that to manufacture the tapered flutes 102, aspecial roller 144 is required, shown in FIG. 4. The roller 144 includesa peripheral surface having a multiplicity of aligned teeth 146 formedthereon. The tapering teeth 146 taper from a narrow first end to awidened second end, as shown more clearly in FIG. 5. It can beappreciated that complementary teeth 147 on an opposing roller 145 taperfrom a narrowed second end to a widened first end. Therefore, as thefacing sheet of the center sheet 108 is fed through the nip of thecomplementary rollers 144, the filter media is crimped to form peaks 104and troughs 106 which taper in alternate directions along their length.It can be appreciated that the beads 124 and 126 provide filter mediawhich is structurally self-supporting.

As shown in FIG. 3, the resulting filter media 100 includes taperedflute chambers 120 which have a closed upstream end and flute chambers122 which have an open upstream end. It can be appreciated that withtapered flutes 102, flute chambers 122 have a larger cross sectionalarea transverse to the flow than the chambers 122 which have theirupstream ends closed. It can also be appreciated that the crosssectional area transverse to the flow of the fluted chambers 120 islarger than the cross sectional area of the closed chambers 122 and theedges of the sheets 108, 112 and 114. In this manner, the filter media100 intercepts greater flow with less resistance. As the flute chambers120 and 122 taper inversely to one another, the ends of the chambers arereversed in size at the downstream edge. With this configuration, it canbe appreciated that the flute chambers 120 have a much smaller crosssection at the closed downstream end of the filter media 100 and theflute chambers 122 have a much larger cross sectional area. Therefore,the flow passes in through the larger openings of chambers 120 and outthrough the enlarged open downstream ends of flute chambers 122. Withthis configuration, flow passes through filter material having muchgreater open space with less resistance, while still providingsufficient filter media area in the same volume.

Referring now to FIG. 6, there is shown a second embodiment of filtermedia, generally designated 200, having asymmetric flutes according tothe principles of the present invention. The filter media 200 includesasymmetric flutes 202 forming substantially narrower peaks 204 andwidened arcing troughs 206. The radius of the arc of the peaks 204 isless than the radius of the arc of the troughs 206 of the asymmetricflutes 202. The filter media 200 includes a center sheet 208 and facingsheets 210, including a first upper facing sheet 212 and a second lowerfacing sheet 214.

The facing sheets 210 are connected by upstream beads 224 and downstreambeads 226. In this manner, the sheets 208, 212 and 214 form chambers 220having their upstream ends closed and chambers 222 having theirdownstream ends closed.

It can be appreciated that with the configuration shown in FIG. 6, theupstream portion of the filter media 200 intercepting flow includes anenlarged opening for the chambers 222. In this manner, increased flow isintercepted by the fluted chambers 222 which then flow through thesheets 208, 212 and 214 and through the chambers 220. In addition, theasymmetric fluted filter media 200 provides for a self-supporting filterstructure.

Referring now to FIG. 7, the open end of the chambers 222 issubstantially larger than the bead 224 at the upstream end and thesurface area transverse to the flow of the sheets 208, 212 and 214. Thisarrangement decreases the restriction at the filter inlet and providesfor improved flow and dust loading capacity.

Referring now to FIG. 8, roller 244 for forming the asymmetric flutedfilter media 200 includes a multiplicity of teeth 246 along itsperiphery. The teeth 246 of a first roller 244 will have a widened outersurface with a narrow trough formed therebetween. The complementaryroller would have narrowed teeth with a widened trough formedtherebetween for intermeshing with the teeth 246. It can be appreciatedthat as the rollers engage filter material fed therebetween, asymmetricpeaks and troughs are formed in the fluted filter material.

Referring now to FIG. 9, there is shown another embodiment of thepresent invention having crushed filter media, generally designated 300.The crushed filter media includes flutes 302 having a crushed upstreamedge 316. The flutes include peaks 304 and troughs 306 formed by afluted center sheet 308. Facing sheets 310 sandwich the center sheet 308to form fluted chambers 320 and 322. A first facing sheet 312 contactsthe upper surface of the flutes, while a lower facing sheet 314 contactsthe bottom of the flutes. The filter media 300 includes an upstream bead324 and a downstream bead 326. The cross section of the flutes from thedownstream end appears as in FIG. 10. The cross sectional view from theupstream ends would be reversed from that shown with the open and closedportions being opposite.

As shown in FIG. 11, the upstream side of the filter media 300 includesa crushed edge 316 along the upstream bead 324. This forms a slopingsurface 328 of the bead 324 and center sheet 308 which engages the flow.The slope provides less resistance while greater flow is achieved, sothat the restriction across the filter media is reduced. It can beappreciated that the filter material and bead engaging the flow at theedge 330 is less than the open area intercepting the flow, improvingefficiency and flow.

The sloped edge can be formed by a number of methods, however apreferred method is shown in FIGS. 15 and 16. An arced or round formingmember 350 is pressed against the upstream bead 324 before the sealingmaterial of the beads is set to provide a quick and easy method offorming an sloping surface 328, as shown in FIG. 15. The forming tool350 may be a ball which is rolled along the upstream bead 324 or arounded member which is pressed onto the media 300. After the depressionis made, the media 300 is cut with a blade 360 or other cutting tool atthe upstream bead 324, thereby forming two strips of filter media 300having a sloping upstream edge 330, as shown in FIG. 16. It can beappreciated that a number sets of widened alternating beads 324 and 326may be applied to a sheet of media 300. The upstream beads 324 are thencrushed as shown in FIG. 15. When the sealing material of the beads 324and 326 sets, the sheet of filter media 300 is cut at beads 324 and 326to form multiple sheets of filter media 300 having crushed upstreamedges 300.

Referring now to FIG. 14, there is shown a fourth embodiment of thepresent invention with fluted filter media 400. The fluted filter media400 is similar to other fluted filter media, but the fluted filter media400 has a modified upstream edge and bead configuration, as explainedhereinafter. As shown in FIG. 14, the fluted filter media 400 includesflutes 402 having peaks and troughs with flutes 420 closed upstream andflutes 422 closed downstream. However, unlike other fluted filtershaving alternating chambers sealed at the extreme upstream face of thefilter media, the flutes 420 include a bead 424 sealing off the flutechamber which is recessed from the upstream edge of the filter media400. The flutes 422 have beads 426 which are at the downstream end.

The filter media 400 provides performance advantages as it can beappreciated that large particles 1000 may accumulate at the upstreamface of the filter media. As shown in FIG. 14, if the particles 1000 arelarge enough, some of the flutes 402 may become completely blocked off.For prior filter media, if several flutes are blocked off, the blockage1000 has greater impact as alternating surrounding flutes are sealed attheir upstream side, creating increased flow redirection around theblocked flutes. However, as shown in FIG. 14, when the flutes 420 aresealed at their upstream side at 424 and recessed from the upstreamedge, a blockage 1000 of an adjacent downstream closed flute 422 allowsthe flow to pass into the upstream end of the flutes 420 and through thefluting sheet or other filter material upstream of the seal 424. In thismanner, the fluid flows into flute 422 where it is forced back throughthe filtering material into the flutes 420 which are open to thedownstream side of the filter. This reduces clogging and provides forbetter flow without pressure buildup or otherwise adversely affectingfilter performance.

In a preferred embodiment, the upstream sealing beads 424 are recessedfrom approximately ¼″ to 1″ from the upstream edge. In this manner, thefluted material is still self supporting while decreasing the effects ofclogging at the upstream face of the filter media 400.

As shown in FIG. 12, the pressure drop for air flow compares flutedfilter media having standard B size flutes to the tapered filter media100 also having a B size flute. In addition, a standard A size flutedfilter media is compared to the crushed filter media 300 having an Asize flute. It can be appreciated that the pressure drop across thefilter, in both instances, is reduced as compared to the standard flutedfilter configuration while having the same filter volume and nominalflute size.

In addition, as shown in FIG. 13, as the filter media becomes loadedwith dust, it can be appreciated that a standard B flute has a muchhigher pressure drop than a B flute with tapered filter media 100. Inaddition, a size A flute for filter media 300 with a crushed leadingedge has a significantly lower initial pressure drop than a standard Aflute.

It can be appreciated that with the present invention, filter media isprovided which has a substantially greater open area transverse to theflow which intercepts the flow. This provides for increased efficiencywith decreased restriction.

It is to be understood, however, that even though numerouscharacteristics and advantages of the present invention have been setforth in the foregoing description, together with details of thestructure and function of the invention, the disclosure is illustrativeonly, and changes may be made in detail, especially in matters of shape,size and arrangement of parts within the principles of the invention tothe full extent indicated by the broad general meaning of the terms inwhich the appended claims are expressed.

1. Fluted filter media comprising: (a) a fluted media sheet secured to afacing media sheet and wound into media for a filter element including:(i) a first sealant bead between a first side of the fluted media sheetand the facing sheet positioned spaced at least 0.25 inch from anupstream end of each flute in the fluted media sheet; and, (ii) at leasta second sealant bead between the facing media sheet and an opposite,second, side of the of the fluted media sheet; the second sealant beadbeing positioned adjacent a downstream end of the fluted media sheet. 2.Fluted filter media according to claim 1 including: (a) an adhesive rowbetween the second side of the fluted media sheet and the facing mediasheet and spaced from the second sealant bead.
 3. Fluted filter mediaaccording to claim 2 wherein: (a) the adhesive row is not a sealantbead.
 4. Fluted filter media according to claim 1 wherein: (a) thefluted filter comprises only one sealant bead between the second side ofthe fluted sheet and the facing media sheet.
 5. Fluted filter mediaaccording to claim 1 wherein: (a) the first sealant bead is spaced fromthe upstream end of each flute of the fluted sheet a distance of atleast 13.7% of a distance from the upstream end to the downstream end ofthe flutes.
 6. A method of filtering air comprising: (a) providing awound media comprising a fluted media sheet secured to a facing mediasheet; and, (b) directing air to be filtered into an open end of a firstset of flutes having a first seal therein at least 13.7% of a distancefrom the upstream end to the downstream end of the flutes, and throughthe first set of flutes; and, (c) diverting the air in the first set offlutes around the first seal by: (i) passage through at least one of thefluted media sheet and the facing media sheet, and into one or moreflutes on an opposite side of the at least one of the fluted media sheetand facing media sheet; and, (ii) passage at least in part back into thefirst set of flutes at a location downstream of the first seal; and,(iii) passage at least in part out from the first set of flutes, throughopen downstream ends of thereof; (A) the step of diverting includingdirecting air flow into adjacent flutes on an opposite side of thefluted media and facing media which are sealed closed adjacent adownstream end.
 7. A method according to claim 6 wherein: (a) the stepof directing comprises directing into a first set of flutes in which thefirst seal is positioned in at least 0.25 inch from inlet ends of eachflute of the first set of flutes.
 8. A method according to claim 7wherein: (a) the step of directing comprises directing into a first setof flutes in which the first seal is positioned with the range of 0.25-1inch from inlet ends of the first set of flutes.
 9. A method of forminga fluted filter media; the method including: (a) securing a fluted sheetto a facing sheet and winding the combination into a media configurationof a filter element; (i) the steps of securing and winding includingproviding: (A) a first sealant bead between the fluted media sheet andthe facing sheet on a first side of the fluted sheet at a location atleast 0.25 inch from an upstream edge; and (B) at least a second sealantbead between the fluted media sheet and the facing sheet along anopposite side of the fluted media sheet and adjacent a downstream edgeof the fluted sheet and facing sheet.
 10. A method according to claim 9wherein: (a) the steps of securing and winding include providing thefirst sealant bead at least 13.7% of length of each flute of the firstflutes from the upstream edge.